Molding is a commonly employed technique for producing parts of simple to complex geometry. Plastic molding techniques may include, for example, injection molding. Injection molding is a popular technique for producing large-scale parts, such as vehicle parts. One part of interest to the present invention is a vehicle bumper fascia.
As would be well understood by one of skill in the art, injection molding typically utilizes a mold that is divided into two mold halves—one half including a mold cavity and another including a mold core. One half of the mold is affixed to a stationary molding machine platen and the other half is affixed to a moving molding machine platen.
As would also be well understood by one of skill in the art, the mating faces of the mold halves create a parting line on the molded part. Even when the mating faces of the mold halves fit tightly together, it is typical that some indication (e.g., a raised line) of the parting line will appear on the molded part.
For at least aesthetic reasons, it is often desirable that the parting line of a given molded part be located along a part area that is not visible to an observer from a typical viewing angle. Placing a parting line in such a location may be desirable on a variety of different parts.
Without limitation, one such part and a part of particular interest in the present invention, is a vehicle bumper fascia. As would be well known to one of skill in the art, vehicle bumper fascias are commonly injection molded from various plastic materials (e.g., TPO). These bumper fascias have a forward or rearward facing surface whose length extends in a width direction along a corresponding front or rear portion of a vehicle, as well as wing sections that extend transversely in the length direction of the vehicle, typically to form a portion of the vehicle's wheel wells.
Such bumper fascias are typically formed using large injection molds having a moving mold half and a stationary mold half. One mold half includes a mold core and the opposite mold half includes a mold cavity, which cooperate when the mold is closed to form the molded bumper fascia. The largest of the parting lines associated with such a bumper fascia can typically be relegated to unseen upper and lower portions of the part. However, it has traditionally proven much more difficult to hide the parting lines created near the free ends of the fascia wings, normally along the area that forms the arch-shaped wheel well flange.
More particularly, the wing portions of the bumper typically terminate in substantially arch-shaped ends so as to form a portion of what is normally a like-shaped wheel well. These wheel well forming portions of a bumper fascia typically include a flange that extends transversely inward to facilitate attachment of the wing end portion of the bumper fascia to the vehicle body—commonly, via screws or other fasteners.
As one skilled in the art of molding would clearly understand, the inwardly extending flanges of the bumper fascia wheel well portions cannot be molded by a mold having only a typical cavity and stationary core, as creation of the flanges requires an undercut in the mold cavity that would subsequently prevent removal of the bumper fascia after molding. Consequently, as illustrated in FIG. 1, known molding techniques for creating such a bumper fascia include a mold 5 with a cavity portion 10, a stationary core portion 15, and outwardly moveable side cores 20 that mate with a corresponding section of the mold cavity to form the wheel arch flanges 25. After molding, these side cores 20 are moved outward to a degree that temporarily deforms the fascia wings and permits the wheel arch flanges to clear the mold cores as the bumper fascia is ejected therefrom.
This known molding technique and mold design adequately function to produce a bumper fascia with inwardly extending wheel arch flanges. However, as can be observed in FIG. 1, the resulting parting line 30 is located on an easily visible (e.g., “A”) surface of the bumper fascia. Thus, even after painting, the parting line is likely to be noticeable.
It should be apparent from the above description that it would be desirable to provide a mold and molding technique that permits the parting line of a bumper fascia in the area of the wheel arch flanges to be moved to a less visible surface—preferably, onto the wheel arch flanges of the bumper fascia and into the wheel well of a vehicle onto which a bumper fascia has been installed. The present invention provides such a mold and molding technique.